[Contribution of nutrient uptake and utilization on yield advantage in maize and potato intercropping under different nitrogen application rates].

Intercropping of maize and potato, as an important intercropping planting pattern, has a prominent advantage of resource utilization and yield. However, contribution of nutrient uptake and utilization to crop yield advantage and its response to N application rates remain unclear. Through a 2-year plot experiment, including maize monoculture, potato monoculture and maize intercropping with potato at 4 N-fertilized levels of N(0 kg·hm), N(125 kg·hm), N(250 kg·hm) and N(375 kg·hm), nutritional contribution of yield advantage of intercropping was studied. The results showed that weighted average uptake of nitrogen, phosphorus and potassium was gradually increased with N application rate in monocultures, but increase followed by a decrease in intercropping. Compared with monoculture at the same N level, nutrient uptake advantage of intercropping was the highest at N, which increased nitrogen, phosphorus and potassium uptake by 14.9%, 38.6% and 27.8%, respectively. However, the nutrient use efficiencies were highest in intercropping at N and N with increment of 3.5%-14.3% for nitrogen, 3.5%-18.5% for phosphorus and 10.6%-31.6% for potassium. Maize and potato intercropping had a significant yield advantage at N and N. Yield advantage in intercropping attributed to improvement of nutrient use efficiency at N while to increase of nutrient uptake at N. To utilize the yield advantage from nutrient uptake, controlling input of nitrogen fertilizer is necessary in intercropping.